Technical Abstract:
Municipalities in the Southern High Plains of TX use land application of treated wastewater extensively. For example, in the Texas Commission on Environmental Quality’s Region 2 counties (Lubbock and surrounding counties), there are ~ 7285 ha of agricultural land over lying the Ogallala Aquifer permitted for land application of treated wastewater. For these lands, an average of 787 mm per year (ranging from 51 to 1778) of irrigation is allowed by permit. The City of Lubbock, TX has conducted land application of treated municipal effluent since the 1930s and currently has ~ 3764 ha and a maximum daily flow of 100 million liters permitted. During the 1960s, groundwater investigations documented a significant mound of high nitrate groundwater, which had developed from over application of effluent; this discovery led the City to change management procedures and initiate a large-scale remediation program. This remediation program has continued successfully in complement with continued land application of treated effluent. A research program was recently implemented to develop, parameterize, and validate a hydrological model to characterize and quantify soil water movement through the vadose zone and potential recharge to the Ogallala aquifer underlying fields irrigated with treated effluent from the City of Lubbock. These efforts will provide an increased understanding on how irrigations should be scheduled and how soil water can be monitored to minimize the impact of effluent application to soil, surface water, and groundwater resources. Initial hydrologic characterization is being conducted on two distinct fields: a perennial grass monoculture (Thinopyrum ponticum) and an annual warm/cool season grass rotation (Lolium L. and Sorghum bicolor). Soil characterization data including electromagnetic induction, soil nutrient concentrations, and soil physical measurement results will be presented.